Last Night's General Meeting Decompression and Next Month

[camp .]

    What a great meeting last night! Thanks to David Schulof and Toborlife for hosting us. Thanks to Nathan Lewis for presenting the BotPDU (Power Delivery Unit), to all the folks who showed up, and especially to those who participated in Show-and-Tell.

    March is our HBRC Challenge month "Phase I."* It will be our 24th Annual, so get your robot running! If you're not currently building, start! Your deadline is the last Wednesday of the month... March 25th.

Challenges

https://www.hbrobotics.org/index.php/challenges/

Thanks,

Camp

* HBRC Challenge Phase I: Bring your robot in some state of "finished."

[Ross Lunan]

Perhaps this was covered by Nathan's presentation which I unavoidably missed: On the ROS Tue evening Feb24 PD subject in a brief exchange, to followup here is a Pinout diagram showing the USB-C 12 Pin assignments x2 for reversal, and a transcription from Gemini on PD DataPins CC1 & CC2 function. Illustrates why it's essential to select a "PD Compliant cable" to power a RP5 in PD mode.  Ross

USB-C what are PD data pins?

USB Power Delivery (PD) data is transmitted over the Configuration Channel (CC) pins (CC1 and CC2), not the USB 2.0 or data pins. A single CC pin is used to communicate between devices to negotiate power contracts, enabling up to 240W (48V/5A). The other CC pin can act as VCONN to power the cable’s e-marker chip.

Key Details About PD and USB-C Pins:
CC1/CC2 (Configuration Channel): These are the primary pins for PD, handling orientation detection, cable identification, and power negotiation.

Data Transfer vs. PD: While PD uses the CC pins for negotiation, actual data transfer occurs on the TX/RX pairs (High-Speed) or D+/D- pins (USB 2.0).

E-Marker Communication: The PD protocol uses the CC lines to read e-marker chips in the cable to determine cable capabilities (power rating, speed, etc.).

Reversibility: Only one CC pin is used at a time, allowing the connector to be flipped.

Power vs. Data Cables:
Full-featured Cable: Includes 24 pins for power (VBUS/GND), CC, and all data lanes (USB 3.x/4).
Charge-only Cable: Often reduces pin count to only 4 (VBUS, GND, and CC) to reduce cost, but still requires the CC pin for proper PD negotiation.

[Pito Salas]

I struggled with identifying my USB cables, not just PD vs. Non-pd but also USB2.0 USB2.1 etc.) This was while I was trying to get my Oak-D-Lite to work.

I found this little device which was very helpful. It’s not too expensive and it does a lot more. For me it was a life saver!

This might be of interest.

[Michael Wimble]

Great device. When you’re at the next meeting out here, I’ll bring my two boxes of cables and I’ll want to borrow the device for a few minutes so I can color-code them. So, I assume you will be at the next meeting here, right? :-)

> --
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> <Screenshot 2026-02-27 at 7.23.48 PM.png>
>
> https://treedix.com/collections/best-seller/products/treedix-usb-cable-tester-usb-c-cable-tester-usb-tester-for-data-transmission-and-power-transmission-cable-testing-resistor-testing-type-c-emarker-for-usb-a-micro-b-micro-b-3-0-type-c-lighting-mini-b
>
> Best,
>
> Pito
>
> Boston Robot Hackers &&
> Comp. Sci Faculty, Brandeis University (Emeritus)

[Pito Salas]

I wish I could be there!

Best,

Pito

Boston Robot Hackers &&
Comp. Sci Faculty, Brandeis University (Emeritus)

> To view this discussion visit https://groups.google.com/d/msgid/hbrobotics/2D27BFE1-3C78-40BF-8E40-B7699C787FE1%40gmail.com.

[Ross Lunan]

Nathan, Much appreciation for your exhaustive "PD" presentation Feb 25. and an introduction to your new BOTPMU board. My best enlightenment was your reveal of the TI TPS25751 Chip (surprisingly only ~$5.00) and its Configurator Utility program. You displayed a page showing a 5v/5a Setting non-standard RPi5 5v/5A profile that your board will support by default. Yeh! That answers the question of the day as to how the "Official WallWart" and 2 of the currently available PD Compliant Boards from Yahboom and 52Pi may work without doing the RPi eeprom edit necessary to deploy an 5V/5A profile  for example the PlusRoc and other DC-DC Downconverters. Looking up close appears to show the use of that Chip. Ross 

On Thursday, February 26, 2026 at 12:34:07 p.m. UTC-5 camp . wrote:

[Ross Lunan]

Following up on this PD subject evaluating a couple cables with my now trusty Treedix Cable Tester:  2 Apple Store 24" usb cables displayed Data Transmission (good!), Power Transmission PD<65W. NO PD2.0,3.0, 3.1. Apparently this means the cable has no E-Marker chip, 60w <3a current limit intended for light laptops and phones/tablets.  Obviously if "Fast Charging"  PD compliant function desired - the Powerand PD 2/3/3.1 must be spected. I guess this means a RasPi5 would not play nicely with this cable though could be used to power relatively slowly and able to sync an iPhone with a laptop. Caveat emptor. Ross  

[James H Phelan]

Which Treedix tester did you get?  How much was it?  Making a wish list.

James H Phelan
"Nihil est sine ratione cur potius sit quam non sit"
Leibniz

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[Chris Albertson]

You should not need to buy a test device to inspect a cable. Your computer has to be able to read this from the cable if it is going to use the cable. So a simple app can format and display this for you. Google will find an app for this that runs on your platform. For Mac there is one called “USB Connection Information” that will tell you everything about a connected cable.

On a Linux PC, the command would be “lstypec” to show the specifications of a connected Type-C cable. Likely you need to install the command from GitHub. Use “lsusb” to find the usb ports in use.

[Pito Salas]

Maybe. The operative word here is “should” as it “should not have to buy a test device”...

But if I am troubleshooting a mystery problem and I am isolating each possible cause then I want to be able to tell with confidence what my USB cable (and each end of it) is doing. Using software to check leaves a lot of variables:

- version of lsusb and how well it supports that particular flavor of hardware and OS
- quality of the usb jack on each end
- feature of the usb cable that is not exercised (e.g. PD)

I am much more comfortable relying on one “built for purpose” test device when I am chasing my tail trying to isolate a problem.

Best,

Pito

Boston Robot Hackers &&
Comp. Sci Faculty, Brandeis University (Emeritus)

> On Mar 16, 2026, at 2:07 PM, Chris Albertson <alberts...@gmail.com> wrote:
>
> You should not need to buy a test device to inspect a cable. Your computer has to be able to read this from the cable if it is going to use the cable. So a simple app can format and display this for you. Google will find an app for this that runs on your platform. For Mac there is one called “USB Connection Information” that will tell you everything about a connected cable.
>
> On a Linux PC, the command would be “lstypec” to show the specifications of a connected Type-C cable. Likely you need to install the command from GitHub. Use “lsusb” to find the usb ports in use.
>
>

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